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meerkt
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2nd hop is 0.0.0.0?

Sat Feb 09, 2019 11:31 am

I noticed my second hop out is 0.0.0.0, with latency that indicates it's external.
(The first hop is the local gateway, as expected.)

What's up with that?
Is this the ISP's doing?
What's tracert actually pinging for that 0.0.0.0?
 
chuckula
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 12:18 pm

I have a feeling that it's an artifact of traceroute since many ISPs suppress [or potentially fake] the ICMP messages that traditional traceroute relies on to produce results.

Try TCP traceroute instead. It might work better.
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meerkt
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 12:51 pm

Same thing with TCP.
 
chuckula
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 1:09 pm

meerkt wrote:
Same thing with TCP.


That's interesting. Based on general stuff I've seen floating around the ether, if that's not the issue then it could be that there is a gateway or a route setup in your system that can end up putting traffic to 0.0.0.0. One offender was the Bonjour service that gets setup if you have iTunes installed, and there could be other sources too.

Under Linux, I would run this command to show all my routes and gateways to check for anything weird:

ip route list
default via 192.168.10.1 dev wlp3s0 proto dhcp src 192.168.10.107 metric 303
192.168.10.0/24 dev wlp3s0 proto dhcp scope link src 192.168.10.107 metric 303


If you are running Windows, I'm not as certain what the command is (ipconfig?)
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chuckula
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 1:32 pm

Another idea: Try tracepath instead of traceroute.

I have a relatively wacky ISP myself here and tracepath seems to work fine.

The tracepath utility is part of the iputils package that's widely installed in many Linux distros, although once again I don't know if it is available for Windows [if that's your OS].
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DancinJack
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 1:40 pm

chuckula wrote:
Another idea: Try tracepath instead of traceroute.

I have a relatively wacky ISP myself here and tracepath seems to work fine.

The tracepath utility is part of the iputils package that's widely installed in many Linux distros, although once again I don't know if it is available for Windows [if that's your OS].

pathping would be closest
re: ip route list - try using "route print" on Windows

btw, you shouldn't worry about the 0.0.0.0 hop. often times it's just a placeholder
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meerkt
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 2:00 pm

The thing is, I don't recall ever seeing something like this, on this ISP or any other.
I did search the web some, but no obvious relevant answer.

No Bonjour here. And wouldn't that entail 0 latency?

The routing table seems normal, comparing to random stuff on the web.

No tracepath on Windows. What specific feature of it you think may be of help? But even if that sidesteps the strangeness, it doesn't explain what's going on.


pathping shows the same.

Placeholder for what?
Not worried, curious to know what it is.
 
chuckula
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 2:07 pm

meerkt wrote:
The thing is, I don't recall ever seeing something like this, on this ISP or any other.
I did search the web some, but no obvious relevant answer.

No Bonjour here. And wouldn't that entail 0 latency?

On Windows there's "route print" for some routing info. It seems normal, comparing to random stuff on the web.

No tracepath on Windows. What specific feature of it you think may be of help? But if even if that sidesteps the strangeness, I'm curious to know what/why/how the common tools show.


Tracepath is not radically different from traceroute but has some more modern features to improve the chances that you'll get a successful path trace. It also uses MTU discovery by defaulf. From what I can tell, the more modern versions of traceroute can perform the same operations, but may require you to enable certain options at runtime to mimic the default behavior of tracepath.
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Ryu Connor
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Re: 2nd hop is 0.0.0.0?

Sat Feb 09, 2019 10:54 pm

0.0.0.0 is the route of last resort. Every network device (including your PC) that can route traffic has that route configured by default. On business class equipment it tends to not be configured by default just in case the network administrator doesn't want a route of last resort (security/isolation).

You've got some sort of interesting software interaction happening to provide that as an answer. 0.0.0.0 is not a broken answer and trying to figure out what weird thing you or your ISP has done to cause that as answer isn't worth chasing down.

Open up a command prompt in windows and type 'route print' and you'll be able to see an example of the route of last resort on your own computer.
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